Tuvix

Returning from an away mission to collect plant samples, Tuvok and Neelix are beamed up together with some alien orchids and emerge as one being. Calling himself Tuvix, he has the memories and skills of both men, but a personality all his own. With no way to reverse the merger, Tuvix takes up duties as tactical officer and cook, impressing Janeway, while Kes struggles to cope with losing both her mentor and her partner. Two weeks later the Doctor finds a way to separate the two men. But Tuvix does not want to die: he argues that he is a person with his own right to live. Janeway weighs his plea against the rights of Tuvok and Neelix, who cannot speak for themselves. When the Doctor refuses to carry out a procedure that would end a patient's life, Janeway performs it herself. Tuvok and Neelix are restored, and Tuvix is gone.